Unloading device for fluid-compressors.



C. WAINWFHGHT & F. J. CARNEY.

UNLOADING DEVICE FOR FLUID COMPRESSORS.

APPLICATION FILED OCT. 22. um. RENEWED MAR. 10. ms.

1 1 1 &.I Patented Apr. 18, 1916.

:IIIII I awwwbom (W [Warm WWUUWZf/M 'I'III: COLUMBIA PLANDURAPH c0., WASHINGTON, u. :24

CHARLES WAINWRIGHT AND FRED J'. CARNEY, OF ERIE, PENNSYLVANIA.

UNLOADING DEVICE FOR FLUID-COMPRESSORS.

Application filed October 22, 1912, Serial No. 727,252.

To all whom it may concern:

Be it known that we, CI-IAnLns WAIN- WRIGHT and FRED J. CARNEY, citizens of the United States, residing at Erie, in the county of Erie and State of Pennsylvania, have invented new and useful Improvements in Unloading Devices for Fluid-Compressors, of which the following is a specification.

The general object of the invention is to refine the construction and increase the effi ciency of what are known as air or fluid triggers for fluid compressors. And to this end the invention consists in combining a fluid actuated controlling device with the fluid actuated trigger mechanism and so designing and arranging the several parts as to render the operation of the trigger mechanism under the control of the controlling device.

Other objects will appear and be better understood from that embodiment of our in vention of which the following is a specification, reference being had to the accompanying drawings forming part hereof, in which Figure 1 is a detail side elevation of the device partly in section. Fig. 2 is an end elevation partly in section of the cylinder of a fluid compressor, showing the device partly in section and elevation and connected to the cylinder. Fig. 3 is a detail elevation of the bracket for connecting the device to the cylinder.

Heretofore, so far as known, it has been customary to assemble a fluid trigger by providing a device such as is shown in the upper half of Figs. 1 and 2, and indicated generally by 5, connecting one end of a pipe as indicated by 6 in Fig. 2 with the chamber 7 in the lower end of the device 5, introduc ing the other end of the pipe 6 into a cylinder 8 depending from the inlet valve cage 9 of the cylinder 10 of the pump mechanism and arranging in the cylinder 8 and directly below and in alinement with the stem 11 of the inlet valve 12, a plunger 13, and finally connecting one end of a pipe leading from a source of fluid pressure, with an upper chamber 14 in the device 5.

In the operation of a device constructed as just described, the piston 15 in the upper end portion of the device 5 lifts when the air pressure in the chamber 14 is sutlicient to overcome the tension of the spring 16, and the tension of this spring may be varied by Patented Apr. 13, 1916.

Renewed March 10, 1916. Serial No. 83,406.

a plug 17 screwed into the upper end of the device 5. Now upon the lifting of the piston 15, a needle valve 18 carried thereby is also lifted and air is admitted from the chamber lat into the chamber 7 from whence it passes through the pipe 6 to the plunger 13 and operates to force the said piston upwardly to effect the lifting of the inlet valve 12. This has the effect of unloading the cylinder 10. When the receiver pressure is reduced below the point which effected the lifting of the piston 15, the spring 16 moves the piston downwardly and effects the seating of the needle valve 18. This cuts off the supply of fluid to the plunger 13 and the fluid entrapped in the pipe 6 and chamber 7 escapes through a vent 19. i

In practice the aforedescribed structure is considerably below required efflciency and especially so when leakage occurs around the plunger 13 or in the pipe 6. Under these conditions this lack of efficiency is particu larly noticeable when the needle valve 18 moves gradually to its seat and is manifested by frequent poppings or unloadings of the cylinder 10. The defect is due to utilizing, for the operation of the controller or that part of the mechanism including the piston 15 and needle valve 18, and the trigger mechanism or that part including the pipe 6 and plunger 13, a single supply of fluid which, if any imperfections, such as leakage, exist in the trigger mechanism can not maintain sufiicient pressure in the pipe 6 to continue the unloading of the pump mechanism at such time when the needle valve 18 is cracked or barely unseated. This results in the pump mechanism again becoming active before the complete closing of the needle valve 18 followed by a rise of pressure in the chamber 14 and the unseating of the needle valve, thus bringing about a second unloading of the pump mechanism at a time when the said pump mechanism would be active if the unloading device were operating with maximum efliciency.

In order to overcome the above mentioned defects, we connect the chamber 14 with a pipe 20 which extends from one of a pair of chambers 21 located ab0ve-a filter 22 at the upper end of a pipe 23 which is connected to the receiver (not shown) of the compressor. In lieu of connecting the pipe 6, as previously mentioned with the chamber 7, we connect with the said chamber a fitting 24 which forms one end of a cylinder 25 and which has an open ended passage 26 arranged so as to effect communication between the interior of the cylinder 25 and the chamber 7. Arranged to slide in the cylin der 25 is a plunger 27 whose upper end is held in contact with the upper end of the fitting 2 1 0f the cylinder by a spring 28 whose lower end bears on the lower head 29 of the cylinder. The plunger 27 is of such length as to clear an exhaust port 30 in the wall of the cylinder and a port 31 which communicates with a chest 32 on one side of the cylinder. The chest 32 and the cylinder 8 which contains the plunger 13, are connected by the pipe 6 and a port 33 located above the port 31 is arranged so as to aline with the transverse duct or passage 34: in the plunger 27 when the lower end of the said plungerbears on the lower head 29 of the cylinder 25. The disposition of the duct or passage34 is such as to efiect alinement of the duct with a chamber 35 in the wall of the cylinder 25 when thelower end of the plunger abuts the lower head 29 of the cylinder and since the chamber 35 is connected with the other of the chambers 21 by a pipe 36, it will be manifest that when the lower end of the plunger 27 is in contact with the lower end 29 of the cylinder a passage will be effected for the compressed fluid from the pipe 23 to the cylinder 8 which contains the plunger 13.

The various elements of the trigger mechanism just described may be of any material found suitable for the purpose and of any preferred or well-known construction. The device as a whole may be connected to any suitable support and for conveniently efiecting such connection, we preferably provide a bracket arm such as shown in Fig. 3 and indicated by 37, at the upper end portion of the filter 22. This construction admits of fastening the device to the cylinder 10 as shown in Fig. 2.

In operation and with the spring 16 adjusted so as to yield only at a predetermined pressure in the receiver of the compressor, the obtaining of such pressure in the chamber 14 effects the unseating of the needle valve 18 and admits the compressed fluid to the cylinder 25. Here the fluid depresses the plunger 27 into contact with the lower end I 29 of the cylinder, whereby to establish T lifting of the inlet valve 12. Upon such reduction of pressure in the chamber 14: as will permit of the partial closing of the needle valve 18, no effect whatever will be had on the plunger 27 for the reason that the reduced sup )ly to the chamber 7 and cylinder 25 will in all cases, be sufficient to maintain the chamber 7 and cylinder 25 full, regardless of the escape through the vent 19 and moreover sufficient to overcome the tension of the relatively weak spring 28. So that the supply for supporting the plunger 13 will not depend on that whichcontrols the piston 15, but upon that which comes through the by-pass or pipe 36. Therefore, leakage in any part of the trigger mechanism will have no effect on the supply for the controlling mechanism.

Vhat is claimed as new is:

A device adapted to be used for unloading a. compressor comprising a cylinder closed at one end, a fitting located at the opposite end of the cylinder and having a passage therethrough, a fluid chest located at the side of the cylinder means for connecting the chest with the compressor, upper and lower ports connecting the cylinder with the chest, means for leading fluid pressure from the chest to the compressor, said cylinder having at its side an exhaust port located substantially at the same distance from the closed end of the cylinder as the lowermost of the first mentioned ports, a fluid pressure inlet pipe communicating with the interior of the cylinder substantially at the same distance from the closed end thereof as the uppermost of the first mentioned ports, a plunger movably mounted in the cylinder, the closed end of the cylinder and the fitting limiting the movement of the plunger in the cylinder, a spring interposed between the closed end of the cylinder and the plunger and tending to hold the plunger above the lowermost exhaust port and in a closed position over the uppermost exhaust port, said plunger having a duct passing transversely through the same and adapted to communicate with the uppermost port when the plunger is depressed against the influence of the spring by fluid pressure admitted through the passage of the fitting, whereby the exhaust port is closed by the plunger and fluid pressure may pass from the inlet pipe to the chest and the means for leading the pressure to the compressor.

In testimony whereof we aflix our signatures in presence of two witnesses.

CHARLES VVAINXVRIGHT. FRED J. CARNEY.

Witnesses:

FRANK P. GILL, Jr., Ones. H. ENGLISH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner 01' Patents, Washington, D. C." 

